1. Field of the Disclosure
The invention is directed to a data capture device and a method thereof, and more particularly, to a data capture device for capturing row data in a burst cutting area (BCA) and a method thereof.
2. Description of Related Art
Due to rampant pirated digital versatile disks (DVDs), it is limited to copy videos or contents from an optical disk having a mechanism of content protection for recordable media (CPRM) so as to protect videos or contents therein from being copied without any permission. Generally, a burst cutting area (BCA) of an optical disk is an area for recording information associated with the copyright and required information for decoding the contents in the optical disk.
For example, FIG. 1 is a schematic view corresponding to a BCA in an optical disk specification. As shown in FIG. 1, each row has 5 bytes, and the first byte of each row is a synchronization byte SB_BCA or resynchronization bytes RS_BCA1˜RS_BCA15. Therefore, the synchronization byte SB_BCA and the resynchronization bytes RS_BCA1˜RS_BCA15 require to be detected in advance so that a following row data (e.g. I0˜I11, etc.) can be decoded.
Furthermore, FIG. 2 is bit pattern corresponding to the synchronization bytes and the resynchronization bytes in the optical disk specification. As shown in FIG. 2, each of the synchronization bytes SB_BCA and each of the resynchronization bytes RS_BCA1˜RS_BCA15 respectively include a sync body and a sync identification code. Here, the size of the sync body is approximately 8 channel bits, and the size of the sync identification code is approximately 4 data bits. Besides, the synchronization byte SB_BCA and the resynchronization bytes RS_BCA1˜RS_BCA15 have the same sync bodies.
Generally, when the optical disk is played, in the related art, a sampling signal is initially estimated, and then, sync bodies and sync identification codes in the BCA are detected by the sampling signal so as to obtain a synchronization signal required by the BCA. For example, an US publication no. 2006/0092798 provides a method regarding how to estimate a sampling signal, and an U.S. Pat. No. 6,414,920 provides a method in connection with how to detect a synchronization signal.
According to US publication no, 2006/0092798, a maximum interval length of a return-to-zero signal is detected. Meanwhile, speaking of the optical disk specification, the maximum interval length is normally 4 T, where a T indicates a time interval of a channel bit. Thus, the maximum interval length described in said publication is divided by 4 so as to obtain the sampling signal. However, when it happens to a situation that signals of the optical disk are not evenly distributed or the optical disk is scraped, it would result in the detected maximum interval larger than normal 4 T and the mistakenly estimated sampling signal. For example, FIG. 3 is a time sequence diagram used for describing that a synchronization signal can not be generated by the related art. As shown in FIG. 3, when a maximum interval length of a return-to-zero signal RZ is larger than normal 4 T, a wrong sampling signal den is generated. At this time, from the return-to-zero signal RZ of 4 T, three signal patterns RZ_pa are captured. However, under a normal situation, from the return-to-zero signal RZ of 4 T, there should be four signal patterns to be captured. Then, at this time, the sync bodies and the sync identification codes can not be detected so that the synchronization signal sync can not be generated.
According to U.S. Pat. No. 6,414,920, the sync identification codes are detected either whether to be 0000 and 0001 in turn, or whether to be continuously 0001 for four times simultaneously. If either of the above conditions is satisfied, a decoding procedure is started to be execute to capture the row data in the BCA. However, when a portion or all of the sync identification codes having four sync bodies of 0001 are destroyed by bolts or scraped, even though the row data in the BCA is not destroyed by bolts or scraped, such method would result in a problem that the sync bodies are searched repeatedly, and the decoding procedure can not be started. In addition, when the sync bodies having the sync identification codes of 1111 are destroyed or scraped, the decoding procedure can not be ended by such method. That is, when the sync bodies having the sync identification codes of 0000 and 0001 are destroyed by bolts or scraped, the decoding procedure can not be executed successfully.